1. Field of the Invention
The present invention relates to a new and improved cleaner for stock suspensions, especially for waste paper-fiber stock suspensions from which there are to be eliminated light particles or both light and heavy particles.
Generally speaking, the cleaner for stock suspensions formed from waste paper, as contemplated by the present development, is of the type comprising a rotatable hollow outer cylinder or cylinder member within which there is coaxially arranged for co-rotation an inner cylinder or cylinder member. An annular or circular ring-shaped separation chamber is located between the outer and inner cylinders and the stock suspension flows in substantially axial direction through such separation chamber. Moreover, this separation chamber is provided with a pump-like inlet blade structure or blade means for the transport of the stock suspension into the separation chamber. A turbine-like outlet blade structure or blade means is arranged after, that is, downstream of the pump-like inlet blade structure or blade means. Leading from the separation chamber is a separate discharge for the light particles, if desired, a separate discharge for the heavy particles and for the cleaned stock suspension.
2. Discussion of the Background and Material Information
A similar type of cleaner or cleaning apparatus for stock suspensions has been disclosed in European Published Patent Application No. 0,037,347, published Oct. 10, 1991 and the cognate U.S. Pat. No. 4,443,331, granted Apr. 17, 1984. A different construction of centrifugal cleaner has been disclosed in Swiss Patent No. 253,544, granted Mar. 15, 1948. The suspension to be cleaned is caused to rotate in the separation chamber upon rotation of the cleaner. Due to the centrifugal force the light particles collect in the direction of the center line of the cleaner whereas the heavy particles are collected at the outer region of such cleaner. Through the provision of separate discharge lines these contaminants or rejects are intended to be separately removed from the good stock, in other words, from the cleaned stock suspension.
While partial success has been realized with such cleaners in practice, nonetheless they possess the drawback that such cleaners require a comparatively large amount of space since they are generally erected in a horizontal position. Furthermore, the cleaning action is unsatisfactory when separating light particles or rejects under unfavorable conditions. The separation of heavy particles or rejects could not be satisfactorily accomplished. Therefore, such cleaners were arranged behind or downstream of equipment for the separation of heavy particles or rejects.